Fabrication of Electrostatically-Actuated, In-Plane Fused Quartz Resonators using Silicon-on-Quartz (SOQ) Bonding and Quartz Drie

This paper reports a novel process to fabricate electrostatically-actuated, in-plane micromechanical resonators made of fused quartz for high-Q microsensor applications. Two key processes - low temperature plasma-assisted Silicon-on-quartz (SoQ) direct bonding and quartz DRIE using C₄F₈/He plasma - have been used in combination with thin metallization to fabricate fused quartz resonators driven by electrostatic force. The proposed method enables wafer-level fabrication of fused quartz resonators readily mounted on the substrate, which is advantageous over the conventional fabrication method of quartz crystal resonators. By using the proposed process, 40-mum-thick laterally-driven fused quartz cantilever resonators have been successfully fabricated. The measured Q-values of the metal-coated fused quartz cantilevers are 21,700~48,900 according to the length of the cantilever.