Fabrication and characterisation of microscale hemispherical shell resonator with diamond electrodes on the Si substrate

Abstract

A self-aligned fabrication method is employed for microscale hemispherical shell resonator with integrated diamond electrodes on a silicon (Si) substrate. The millimetre-scale three-dimensional (3D) hemispherical shell resonator, with integrated electrostatic excitation and capacitive detection transducers for full control of the resonator, is fabricated on the Si substrate by employing a microelectromechanical systems process. The eight integrated diamond electrodes evenly distributed outside the hemispherical shell are fabricated using a self-aligned method, which ensures uniform capacitive gap along the whole circumference. The Boron-doped polycrystalline diamond, a material with low thermo-elastic damping and low surface losses to reach the high quality, is used as the millimetre-scale 3D hemispherical shell resonator with integrated electrodes. The fabrication process enables the production of almost perfect hemisphere mould (<2% roundness variation) with an average surface roughness of 3 nm. Vibration modes and frequencies are carried out by a scanning laser Doppler vibrometer; the elliptical mode frequency is determined to be at 81.3 kHz, with the two M = 2 degenerate modes having a relative frequency mismatch of 0.86%. This process can be further optimised to fabricate high-quality and full-symmetric microscale hemispherical resonator gyroscopes in batch.

Recent Advances in MEMS-Based 3D Hemispherical Resonator Gyroscope (HRG)—A Sensor of Choice

“…Disadvantages include the existence of striations and bubbles in the glass and roughness of the sidewalls of the hemisphere, where most of the strain energy is located. Liu et al [ 136 ] used a similar method and materials to fabricate an HRG.…”