Authors: J. Yan and A.A. Seshia
Affilation: University of Cambridge, United Kingdom
Pages: 577 - 580
Keywords: micromechanical resonators, etch holes, mems modeling
Micromachining processes such as surface machining of polysilicon microstructures or SOI-based processes often require etch holes to be created in the structural layer for purposes of releasing the mechanical structures. The present work examines the effect of the nature and density of etch holes on the resonant frequency of micromechanical resonators. Micromechanical resonators find applications as electronic filters or as timing references in oscillators and any process-induced offset in resonant frequency can significantly affect system performance. A general analytical formulation based on the Rayleigh-Ritz principle is used as a starting point to model the resonant frequencies for microstructures of a given topology. The analytical approach is compared to finite element simulation results for a multitude of resonator topologies for varying etch hole size and location. This analytical model enables the formulation of design rules that allow minimization of resonant frequency offsets in MEMS resonators due to the presence of etch holes.