Capacitively activated torsional high-Q resonator

The fabrication and testing of a capacitively activated torsional high-Q resonator is presented. A schematic cross section of the construction for electrostatic excitation and measuring is shown. The structures are etched from both sides simultaneously in KOH, resulting in a symmetrical cross section of the torsional bar, which could be approximated for the calculation of the resonance frequency by an elliptical cross section. After the metal mask step the resonator in the middle is etched down about 10 microns to have space to oscillate. Then glass plates with electrodes are bonded anodically to the decoupling part. By using silicon directly as a counter-electrode, no supplementary layers have to be deposited on the torsion bar, thus leaving, in principle, the Q-factor unaffected