Many MEMS devices which are thermally and/or electrostatically actuated contain moveable components which may undergo contact. The behavior is further complicated when hysteresis is exhibited after contact. Generally, MEMS devices consist of multiple materials with different mechanical and electrical properties. These factors pose a challenge for modeling highly non-linear MEMS behavior. This paper present an improved approach to modeling contact and hysteresis between any two bodies in a MEMS device. In particular, the three assumptions are relaxed. First, previous methods for modeling contact were able to model only a single dielectric layer. The new approach is capable of modeling multi-dielectric layers. Second, previous modeling methods required the specification of contact faces. This restriction has been generalized to specifying contact entities. Third, previously, modeling methods required an air stop gap assumption above a conductor to avoid numerical difficulties in electrostatic calculations. The new approach developed removes the air stop gap assumption. More realistic mechanical contact is simulated. Electrostatic and thermal driven actuation is considered. A number of case examples is presented to demonstrate the utility of the new contact and hysteresis approach. First a suspended test-beam structure is analyzed under different sets of boundary constraints and loading. Then, contact of an electrostatically actuated deformable mirror is analyzed.

Date Published: 10 March 1999
PDF: 8 pages
Proc. SPIE 3680, Design, Test, and Microfabrication of MEMS and MOEMS, (10 March 1999); doi: 10.1117/12.341201

Published in SPIE Proceedings Vol. 3680:
Design, Test, and Microfabrication of MEMS and MOEMS
Bernard Courtois; Wolfgang Ehrfeld; Selden B. Crary; Wolfgang Ehrfeld; Hiroyuki Fujita; Jean Michel Karam; Karen W. Markus, Editor(s)