Demonstration of sub-1 Hz structural symmetry in micro-glassblown wineglass resonators with integrated electrodes

We demonstrate, for the first time, sub-1 Hz frequency symmetry in micro-glassblown wineglass resonators with integrated electrode structures. A new fabrication process based on deep glass dry etching was developed to fabricate micro-wineglasses with self-aligned stem structures and integrated electrodes. The wineglass modes were identified by electrostatic excitation and mapping the velocity of motion along the perimeter using laser Doppler vibrometry. A frequency split (Δf) of 0.15 Hz and 0.2 Hz was observed for n = 2 and n=3 wineglass modes respectively. Frequency split stayed below 1 Hz for DC bias volta ges up to 100 V, confirming that the low frequency split is attributed to high structural symmetry and not to capacitive tuning. High structural symmetry (<;1 Hz) and atomically smooth surfaces (0.23 nm Sa) of the resonators may enable new classes of high performance 3-D MEMS devices, such as rateintegrating MEMS gyroscopes.