Finite Element Modeling of Resonating MEMS Micro-Heater Structures for Design Verification and Optimization

J.V. Crosby and M.G. Guvench (USA)

Keywords

MEMS, Microheater, Finite Element, Modeling

Abstract

The object of this project is to develop finite element computer models of SOIMUMPs fabricated MEMS microheater structures to predict their performance accurately for use as a design verification and optimization tool. Primary performance criteria for the microheaters are (1) temperature uniformity, (2) high heating efficiency and (3) fast thermal response time. Models of SOI-MEMS micro-heaters were developed employing COMSOL Multiphysics® platform. In order to establish the subdomain and boundary conditions for such microscaled structures, parameters were extracted by comparing experimental displacement results to FEM simulated displacement results of a hot-arm-cold-arm microgripper (thermal microactuator) structure, fabricated on the same wafer with the microheaters. Results of the microgripper experiments were then used to narrow the range of plausible values for a comprehensive sweep of our primary design, the resonating microheater. Parameters to be established are temperature coefficient of resistance and convective (to air) heat transfer coefficient; values of each in the microgripper providing most accurate agreement with experiment are found to be .0055°C-1 and 200/100 (top/bottom and sides) W/m2 /°C respectively. Finally, results of the microgripper-guided parametric sweep of the microheater show a maximum range of temperature differences from 2.87% at 32°C to 4.71% at 270°C and very high heating efficiencies (4.29°C/mW – 8.42°C/mW). Thermal time constants were from 2.38ms to 1.40ms.

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