10 August 2000 Mechanical effects of fatigue and charge on CMOS MEMS
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Proceedings Volume 4180, MEMS Reliability for Critical Applications; (2000) https://doi.org/10.1117/12.395699
Event: Micromachining and Microfabrication, 2000, Santa Clara, CA, United States
Abstract
CMOS MEMS devices, fabricated from up to 13 layers of materials to create independent conducting paths, are subject to incremental fracture at high stress and to charging effects. This paper expands on preliminary reserach, which has revealed several stages of change in CMOS MEMS physical properties as they are exposed to resonant motion. Cracks are the first induced inside the stiffest lasyers, often silicon dioxide, in laterally resonant test structures with cyclic stress of 620 Mpa. Prior to cracking, the aluminum top layer of the structure can also deform, which affects the electrical integrity of the conductor. Measured frequency reponses of folded-flexure resonators demonstrate a nonlinear Duffling effect, producing mushroom-shaped resonant peak. Cyclic stress of 70 Mpa at the maximal stress points was insufficient to induce significant mechanical fracture in foled flexure resonators after 5 billion cycles, however an onset of change in stiffness was detected. Devices with a fixed dc actuation voltage experienced a change in electrostatic force attributed to charge accumulation in polymer and oxide layers. The force decayed with an approximate one-hour time constant while resonant frequency and quality factor remained constant.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kevin M. Frederick, Kevin M. Frederick, Gary K. Fedder, Gary K. Fedder, } "Mechanical effects of fatigue and charge on CMOS MEMS", Proc. SPIE 4180, MEMS Reliability for Critical Applications, (10 August 2000); doi: 10.1117/12.395699; https://doi.org/10.1117/12.395699
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