P2O-6 Design of GaAs Resonant Micro-Beams

This paper reports on GaAs resonant microbeams for mass sensing applications. We present a resonant GaAs sensor driven by a lateral field excitation and given a frequency dependent voltage as output. Thanks to an analytical model of piezoelectric excitation, we determine potentially interesting geometries of beams for quasi extensional or quasi shear modes on a (110) wafer. The piezoresistive detection of time dependent stress can be achieved by use of p-GaAs gauges connected in a bridge circuit. The simulator TENSOSIM which is elaborated to furnish etching shapes for 2D or 3D micromechanical structures is used to derive at any etching time the cross sectional shape of GaAs beams micromachined in a H₂SO₄:H₂O₂:H₂O solution. Influence of misalignment on the performances of the micromachined sensor is evaluated and reveals small departures