Dependence of the resonant frequency of micromachined gold microbeams on polarisation voltage

We demonstrate the feasibility of micromachined tuneable gold cantilever beams. The test structures, composed of a deflectable cantilever microbeam, two lateral driving electrodes and a working part, are fabricated using a micromachining process with a single mask. The microbeams are typically 1 mu m wide and 2 mu m high, with variable lengths ranging from 40 to 60 mu m to achieve natural resonant frequencies (f(0)) greater than 100 kHz. These resonators are electrostatically excited with a signal: nu(t)= V-p + nu sin omega t. Varying the polarisation voltage (V-p) produced a shift in the observed resonant frequency (f(obs)) of a few percent around f(0), which makes this system tuneable. We describe the fabrication process, the frequency response and the frequency tuning of this device. (C) 1998 Elsevier Science Ltd. All rights reserved.